Upgrading KDE Plasma to the only stable 5.17.4 leaves left-click on the desktop with no effect ; middle-click + right-click continue to work as expected. In ~/.config/plasma-org.kde.plasma.desktop-appletsrc , there is a line under [ActionPlugins][0] : LeftButton;NoModifier=org.kde.applauncher . This should make a left-click open the applications menu. In fact, when the left button on the mouse is clicked, nothing happens. When the applauncher is assigned to RightButton , a right-click correctly causes the menu to open. This offers a work-around, but leaves only 2 buttons functional. The left button on my mouse continues to work normally otherwise & other users have reported the same problem on the users' mailing-list.
We don't change anything downstream. If this is a bug, then please submit it upstream.
Upstream report: https://bugs.kde.org/show_bug.cgi?id=413104 Known issue since 5.17.0 As reported (also on the mailing list) folder view as desktop plugin works as expected.
Thanks for investigating!
We can only leave this for upstream to solve. Feel free to inform us of any fix we can backport earlier than the release it would appear in.